as you might have alread read in the PacMania thread I am experimenting with porting X68000 games to the Atari ST.

The idea so far is to disassemble X68000 executable binaries in a way that the resulting source code quality is as good as the original so that you only need to rename the most important labels to understand how the game works. More important is that the reassembled version of the executable binary is identical to original as well.

For this task I have already written a disassembler which works fine so far (some mnemonic bugs are still present) in combination with the human68k and the m68k-atari-mint toolchains.

The first experiment was PacMania and the game logic already runs on the Atari STE (please see the PacMania thread for an example).

What are your thoughts, ideas and/or comments on that. Are you interested in some technical details? Please let me know.

i read with interest the Pacmania thread, and when you popped up in there with your ideas about x68000, i must say I think the idea is genius!

As i understand it, the X68000 is heavy on the custom chips, and it makes sense to me that it would in fact be easier to port these games than to make enhanced versions of existing ST titles. On an ST/E there's all manor of ways to draw sprites/backgrounds, but if you have a custom chip handling sprite/background draws, then I would imagine it would be much easier to intercept and replace the calls to the custom chips than unpicking exotic software based routines..

I tried to test the Pacmania X68000 adaptation you linked on the Pacmania's thread (http://atari-forum.com/viewtopic.php?f= ... &start=250) but I don't know if I have to do something special:I copied all files in a 1,44MB disk (don't fit in a 720KB one) and tried to execute the PMSYS.TOS on my Atari Mega STE 4MB, but nothing happens. White screen, cursor on the left-up corner, and goes back to the desktop.

distantminds wrote:As i understand it, the X68000 is heavy on the custom chips, and it makes sense to me that it would in fact be easier to port these games than to make enhanced versions of existing ST titles. On an ST/E there's all manor of ways to draw sprites/backgrounds, but if you have a custom chip handling sprite/background draws, then I would imagine it would be much easier to intercept and replace the calls to the custom chips than unpicking exotic software based routines..

Exactly. Another advantage is that the X68000 has no collision detection like the Atai 800 XL or C64 which would cost a lot of CPU power to emulate. So in this case the complete logic runs on the CPU.

Zamuel_a wrote:What about dissamble a SEGA Megadrive game? It feels like it would be more or less the same as a X68000 game so maybe could be done with the same dissambler.

I am currently not aware of special hardware features of the SEGA Megadrive which would be problematic like the above mentioned collision detection but yes: that could be another target for porting games.

Also the NeoGeo is a potential candidate.

qq1975b wrote:I copied all files in a 1,44MB disk (don't fit in a 720KB one) and tried to execute the PMSYS.TOS on my Atari Mega STE 4MB, but nothing happens. White screen, cursor on the left-up corner, and goes back to the desktop.

I have tested the executable under Hatari emulating an STE with 4 MB and TOS 1.62. However running the test under Steem crashes... well I'll take a look at it. It seems to be a problem calling Trap 15 functions in a Line F exception. Please stay tuned.

qq1975b wrote:I tried to test the Pacmania X68000 adaptation you linked on the Pacmania's thread (http://atari-forum.com/viewtopic.php?f= ... &start=250) but I don't know if I have to do something special:I copied all files in a 1,44MB disk (don't fit in a 720KB one) and tried to execute the PMSYS.TOS on my Atari Mega STE 4MB, but nothing happens. White screen, cursor on the left-up corner, and goes back to the desktop.

I don't know so much about the X68000 system, except that it was faster than Atari and used 65.536 colors so it seems like it would be better to make this conversion for a Falcon than on a regular STE.

Zamuel_a wrote:I don't know so much about the X68000 system, except that it was faster than Atari and used 65.536 colors so it seems like it would be better to make this conversion for a Falcon than on a regular STE.

Agreed. Focusing the Atari Falcon 030 as the main target was the initial goal for me as well.

The "slowest" X68000 runs at 10 MHz. However, some games seem to have a very low CPU performance requirement so that an Atari ST(E) version can be considered as well.

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qq1975b wrote:I tried to test the Pacmania X68000 adaptation you linked on the Pacmania's thread (http://atari-forum.com/viewtopic.php?f= ... &start=250) but I don't know if I have to do something special:I copied all files in a 1,44MB disk (don't fit in a 720KB one) and tried to execute the PMSYS.TOS on my Atari Mega STE 4MB, but nothing happens. White screen, cursor on the left-up corner, and goes back to the desktop.

qq1975b wrote:I tried to test it again on my Atari Mega STe 4MB, 2.06 UK. It didn't work. Makes the same than the earlier version: white screen, cursor on the top left corner and back to the desktop.

It worked on Steem emulator 3.3.0 (it showed pacman on the low left corner in different views).

Well, thanks for trying anyway. Unfortunately I have only my Falcon here to test the binary on a real machine (in fact, only a small fix within the Line F handling was necessary to get it working on the Falcon). Probably I need to dust off my STE to see what's wrong.

qq1975b wrote:I tried to test it again on my Atari Mega STe 4MB, 2.06 UK. It didn't work. Makes the same than the earlier version: white screen, cursor on the top left corner and back to the desktop.

It worked on Steem emulator 3.3.0 (it showed pacman on the low left corner in different views).

Well, thanks for trying anyway. Unfortunately I have only my Falcon here to test the binary on a real machine (in fact, only a small fix within the Line F handling was necessary to get it working on the Falcon). Probably I need to dust off my STE to see what's wrong. Sascha

What about Hatari? I've understood that its latest version (1.6.2) has now more accurate STE emulation than Steem.

(Steem's GUI debugger is much nicer to use, but Hatari's command line debugger is also fairly powerful, especially with the latest updates in Hatari repository.)